So How did you do?  Did you build you troubleshooting guide for no Power?  Did you start?  I hope so, the best way to do anything is to “jump in” with both feet or “go for it”. Nike’s ad is in a similar vein: “Just Do It”

As promised, I’ll show you my troubleshooting guide:  troubleshooting-procedure_no_power  It is a Microsoft Word document so you can take it and adapt it for your own use. 

Some notes as you read through the procedure.  I tried to make it as generic as possible without becoming overly complex.  If you have a specific appliance down to the make and model, you can make a very concise procedure that is specific to your appliance.  You need to have some common sense while using this.

Notes:

1. Does the device have a power applied indicator?  A couple of my PC’s have lights on the back near the power connector that light if AC is applied.  Others show power on by lighting or blinking the LED’s on the front some have no indication.  Only our newest TV has a power applied LED visible when power is applied but the set is “OFF”.  It is actually indicating that the power supply +5Vsb (standby) is on
2. When checking fuses, always use an ohm meter.  I’ve seen fuses where the link was broken below the glass envelope and so visually appeared to be good.
3. Most consumer appliances, TV’s VCR’s etc included do NOT have fuses accessible from outside the cabinet.
4. The standard legal disclaimer is don’t attempt any of this unless you’re qualified to do so.  I can’t judge or validate your capability from behind a computer screen.  You’re a big boy or a big girl and need to make your own responsible decision. 
5. I recommend having a printed out copy right beside you as you do your work.  Re-arrange the cells so that you have room to write in them.  Make this a working document. 
6. I recommend adding a column for the date & time.  You might even have a start/stop time.  It will allow you to evaluate yourself or your staff’s ability to accurately & quickly perform the steps.   If you add enough columns you might want to change the orientation of the paper. 
7. Notice that the footer of the document tells you a couple of things.  It tells you the title of the document so you can find it on your computer when you forget where you saved it and, it tells you how many pages there are so you can ensure that you have the entire procedure every time you use it.  I use this so often for my procedures that I have created a macro that does the footer for me automatically.  You might want to do the same.

If for some reason you can’t open the document, let me know and I’ll convert it to pdf and post that version too.  Again, you should really have it as a document that you can manipulate, change and edit.  Till next time…  RD

As I think of tips I’ll post them and once I get enough, I’ll collect them on a single page so that they’ll be easier to find.  You may have noticed some random part numbers appearing on the site.  Since I’m always taking things apart and figuring out what they do, I’ve decided that I’d start posting any of the datasheets that I research on my website.  I don’t intend to be a “one stop shop” or complete repository, but as I figure things out, I’ll post the datasheets here.

First Tip:

As you take things apart, photograph them with a digital camera.  Do it with good lighting and, if appropriate, write yourself some notes:  “…when I pulled the back off the three screws across the top were longer than the four across the bottom.”  I’ve been doing this ever since I got my first digital camera.  It only had a 480 x 640 resolution and had no screen to see how the image turned out, but still I used it.  It has been indispensable.

1a. As you’re disassembling, if you don’t want to write yourself notes, use a voice recorder, your cell phone, MP3 player or any other device you have that allows you to record your voice.  My cell phone is a TREO 650 that I installed a voice recorder program on.  I set the file naming to include the date and time.  I don’t even have to think about what I’m doing.  Press a couple of buttons and I’m recording.

Moving parts

Tip 2 relates to moving parts.  I had a CD changer that would become difficult to open.  What I did was dis-assemble the case and then arranged it on the dining room table with LOTS of light and I set my VHS video camera up on a tripod over the mechanism.  The camera had a “high speed” mode which I engaged.  I then cycled the CD player until the mechanism stuck.  I was able to play the tape back and figured out what was causing the problem.  Mind you this was a 1989 vintage consumer camcorder, so high speed wasn’t like the ones they use on Myth Busters to catch the bullet tearing apart the crash test dummy.  So anything you can buy today will probably work.  Give it a go!

Saving screws…

For tip 3 you need to do a little assembly.  You’ll need:

• Shoebox lid (bigger is better)
• Some super-strong rare-earth magnets
• glue
• 3×3 Post-it notes
• pen, pencil or marker

Glue the magnets to the top(outside) of the lid several inches apart, at least 4.5″ apart.  Hopefully you have big feet and can get six or more magnets on the lid.  After the glue dries, turn the lid over and mark where the magnets are.   You’re ready to go.  The next time you take something apart, write on the post-it note where the screws came from: (top cover, bottom cover, HV shielding, power supply mounting, etc.)  stick it over one of the magnets and then put the screws on it.  The magnet should hold them in place, on the post-it note until it’s time to put it back together.  Other things you can do is number the post-its to correspond with the order, you could name the parts they go to, you could write down the inventory of screws for that step.  Remember, the more information, the better.  After reassembly, you can throw out the post-its.  OR, if you’re really clever, you’ll save all the information you wrote down into a notebook (database) so that you’ll have the information for the next time that make and model comes in the shop.

A simpler alternative is to use either a muffin baking tray or an empty egg carton. These have the advantage of being very easy, but it’s somewhat harder to categorize and classify information about where the screws came from.

(…continued)As I mentioned at the end of the last post, I’ve never owned an electronic repair shop.  In addition to all the things I mentioned in that post, I’ve worked in the military aboard nuclear submarines, I’ve worked in the chemical industry and the semiconductor industry.  In every case, the success of the organization has come down to the ability to doing the right thing, correctly, the first time, every time.

I can’t imagine any organization or business that wouldn’t have

• My garden tiller is hard to start.  Once it starts, it runs fine for about 10 minutes at which point it stalls if it is taken past half throttle.   If it is picked up so that the engine can run unloaded, it runs fine.  Again, once loaded it bogs down and quits. I’ve cleaned the air filter, fuel filter and spark plug.
• The TV works fine for some period of time and then just shuts itself off.  If turned back on, it makes a loud screeching sound for about a second and then runs.  It will shut itself off again, in less time than before. This continues with the time getting shorter and shorter till it gets to the point that it runs for about 6 minutes max.
• The dryer won’t turn.  I can hear the motor running and it blows air but the drum won’t turn…
• The computer boots but the shuts off after 15 minutes.  When first restarted it goes to “safe” mode.

Questions? Let’s ask questions!!

Don’t be shy about asking questions.  When you go to the doctors office because you don’t feel well, they don’t just give you a shot and send you home.  They ask you questions about your symptoms, they take some objective information about you like:

• Height
• Weight
• Blood Pressure
• Pulse
• Temperature

When you get to the doctor, who’s seen all the information, they usually start with an open ended question like “I see from the notes that this started several days ago, describe how you feel now…” All the while, they’re looking in your ears, nose, throat and perhaps listening to your heart and lungs.  They then probably ask more specific questions:

• Is it only on the right side?
• Always on the right or does it “move around”?
• Does the intensity change?

In some respects, the doctor’s job is easier.  They can ask questions to get information.  The questions can be in random order.  As an electronics repairer, you get one chance to ask questions (usually) and the answers tend to be less than definitive.  You can’t talk to the device, you have to probe, prod and investigate.  Back we go…

Beginning the repair

Based on the symptoms, you would want to ask additional questions, perhaps, or just dive right in.  The thing you want to develop is a troubleshooting matrix.  What I mean by this is something that reminds you of what to check first.  Just like the owners manuals for most appliances that tell you go over the simple things first (my washing machines manual):

• Is it plugged in?
• Is the circuit breaker turned on?
• Is the water turned on?
• Is the lid/door shut?
• Is the load unbalanced?
• Is the child lock activated?

If you are going to run an electronics shop the most common complaint will be:

It won’t turn on

You want to check the obvious and simple things quickly as you don’t want to march off down the wrong path and start removing components when the thing just needed a new fuse.  The perfect examples I have of this are:

• A friends’ toaster oven quit working. It turned out to be the thermal fuse.  Trouble shooting time was  under 10 minutes.
• Another friends’ toaster quit working.  The problem ended up being that the line cord had broken internally. Trouble shooting time 2.5 hours.

In one case, you can tell your customer that you want $25 for the repair.  In the other case, if you tell them $200 to repair, they’ll laugh and go buy a new one.  In the second case, if the trouble shooting had started with: is there power inside the toaster?; the time would have been substantially less.

Homework

So the thing you want to have is a logic diagram that has you check the common things quickly & thoroughly.  Here is your homework assignment:  Make yourself a troubleshooting logic diagram that covers the first part of a repair, isolating a power problem.

At the below left is a sample logic diagram. It represents entering a room where you want to turn on a lamp that is connected to the wall switch next to the entrance doorway.  It is not all inclusive, (it never asks if the power is on to the room circuit), but it give you an idea of the overall thought process for getting the light illuminated in the room.  Click on the image to view it full size.

I hope this helps you with your diagram. Don’t worry about getting it perfect at this point, don’t worry if you only have a couple of things to check.  The important thing is to start thinking about it and documenting (writing it down) your thought process.  The next thing we’ll create is a troubleshooting checklist, based on this diagram.

Additionally, we’ll create a troubleshooting log.  This will be a uniform way of writing down what it is that you have done and what the results are.  For involved, complex,  troubleshooting this is one of the most important things to have.  Why?  If the problem is complex enough that you can’t solve it in one session, you’ll want to be able to easily remember where you were and what you did or didn’t do.  Or, more likely, if you are just starting out you have to do everything.  You have to answer the phone, you have to answer the door and deal with whatever distractions come your way.  If the distraction is important, you may decide to keep dealing with it, or with something related to it, rather than resuming your troubleshooting immediately.  Having a consistent way of doing the troubleshooting and documenting it will be helpful.  Looking to the future, when you aren’t the one answering the phones, you will likely have an apprentice or two.  If they get stuck or can’t figure something out, it will be immensely easier for you to troubleshoot if you have a well documented log.  Or perhaps you want the two or three apprentices to trade off on their troubleshooting, again this will be a useful tool. 

OK, write up your diagram.

(…continued)

From the generalist to the specialist

(Remember from part one that my mechanic had figured out nothing that I hadn’t already  figured out and had sent me to a automotive electric specialist. ) On one hand I was elated that I was as smart as the guys in the shop on the other hand I was bummed that I still didn’t know what was wrong, the car wasn’t working right and I’d spent 4 hours in the shop with my car.  On getting to the automotive electric shop I strolled in and asked for Dan.  The guy said “That’s OK, describe your problem and we’ll see if we need to get him involved.”  I relented and described the problem it in gory detail.  He turned to one of the other guys, Tim I think, and rattled off some commands about checking the voltage regulator and the ground.  I assured him the voltage regulator appeared to be functioning properly.  He smiled and motioned me towards Tim.  Tim was under the hood for all of about 90 seconds before coming out. 

What did I do?  Took it home and had to figure it out.  I checked the operation of the voltage regulator and it was the same.  So I unhooked the copper strap and could see the voltage regulator go to the limit and within a few seconds could see bubbles in some of the battery cells.  I reconnected the copper braid and the voltage regulator output reduced and the bubbles ceased within a minute or so.  I turned off the engine and said to myself: WHY? I looked and looked and finally I realized what was happening.  The alternator negative lead was connected  to the engine block.  The engine was mounted by hard rubber mounts to minimize the vibration and noise into the car.  The voltage regulator was mounted and grounded to the chassis of the car.  The strap is what made sure that the two (chassis and engine block) were at the same potential.  Without the strap, the voltage regulator couldn’t “see” the voltage so it commanded max output.

What’s the point?  I later found out that the guy I spoke to was, in fact, Dan.  He had been doing this for so long, he was able to diagnose the most likely ailments very quickly.  He had “practiced perfectly” for decades.  I had done the right troubleshooting, but was unable to draw the right conclusions, and didn’t quite go far enough.  None of the books specifically mentioned verifying that the voltage regulator and alternator had the same ground references.

Does Practice really make Perfect?

Which takes us back to our saying: “Practice makes perfect.”   This really isn’t completely true as my driver education teacher taught me more than 30 years ago.  The expression that he preferred and used was: “Perfect practice makes perfect.” His explanation was simple “If you practice making a mistake in the car with me sitting next to you, you’ll do the same when I’m not sitting here.”  I can, to this day, remember the grin on his face as I tried to pull away from a stop sign and the engine merely revved and we went nowhere.  It seems I had tried to do a “California stop” even though I was in beautiful eastern Pennsylvania.  For the uninitiated, a California Stop is where you slow the car way down, but never completely stop.  Remember the sign does say “STOP” it doesn’t say “stop only if”, or “roll”.  It says stop.  When my oldest child approached driving age, I reassessed my driving habits and made some adjustments.  I realize that they learn a lot from example, so I wanted to be sure to be doing the right things.  Here I am again, four years later with number two teenager.  Time to re-evaluate my driving, again.

What does any of this have to do with running an electronics repair shop?

Although I’ve never owned an electronics repair shop, I have fixed televisons, computers and all sorts of electrical and electronic equipment.  I’ve worked on some very complex military electronics systems including an inertial navigators, radar, time standard, radios etc.  [to be continued...]

Practice makes perfect!  (or does it)

This is an expression often heard as a child when learning something new like playing the piano, or any musical instrument for that matter. It is used in sports, whether it is the child learning to throw and catch a baseball or pass a soccer ball or even tying a shoe. It applies equally well to the older person learning golf and how to swing the club. It applies to anything that we do or expect to do on a repetitive basis. Most assume that it only applies to muscular activity, but it applies to the use of your brain too.  (Remind me for examples)

Collect Data, Analyze Symptoms

After getting the vehicle home, I did some initial inspections the voltage was around 12 volts, a bit low. As previously mentioned, all of the battery cells were completely dry (this was before the advent of “maintenance free” batteries. I carefully refilled all of the cells with distilled water and ran the engine at a high RPM to charge the battery. Everything seemed fine. What didn’t make sense was that the electrolyte was gone. I decided to check it every couple of days. I got a piece of notebook paper and made a simple table showing the date and cell number. I stuck a plastic drinking straw into each cell and recorded the level. I noticed after about 3 days that one of the cells levels was dropping faster than the others. In retrospect, this is not unusual as the battery is actually 6 distinct cells. I decided to check the electrolyte level again, but with the engine running. This time I noticed in a couple of the cells there were bubbles. The bubbles kept coming. Having read a bit about the lead acid storage battery and the basics of the automotive electrical system, I knew that these were gas bubble of either hydrogen or oxygen. The gases are formed as a natural part of the charging cycle. The thing that was interesting to me was that I could see them. Perhaps the water wasn’t evaporating but rather electrolyzing. Perhaps a problem with the charging system? One thing I tried was to rev the engine while looking, I could see the battery “boil” and all cells bubble as I increased the RPM. My thought was that the voltage regulator wasn’t reducing the signal to the alternator so it was overcharging the battery. Essentially all unused output into the battery…

Research

So back to the book store to read some more on electrical systems. (Although the internet had been invented it, was largely in use by academics and military.) I read a book on the automotive electrical system and learned all I could about the voltage regulator. In those days, it was a simple relay. The basic premise of operation was that if the car was on and the alternator running, it would control the amount of current to the field coils of the alternator to adjust the output of the alternator. As the demand for current went up, it would increase the signal so that the output would increase. It was essentially a relay that shut it’s contacts if the sense voltage got low and opened if it got high… OK. I took my multimeter and using the techniques described in the book, verified that the regulator opened and closed its contacts at the right voltages.

Uncle!

Admitting defeat, I took the car to my mechanic. They worked on it for over 4 hours. I, being the nosy teenager that I was, was right alongside them the whole way, “correcting” them and pointing stuff out to them. They determined that the alternator was fine and could produce plenty of output. They determined the battery was very sick and should be replaced before it got really cold. I said I’d wait until we knew what was wrong and was corrected before putting in a new battery.

Defeated, Yet Again!

After spending all morning on it, and baffling all four of the guys in the shop, they admitted defeat. “OK Kid, go down to Dan’s Auto Electric and ask for Dan, no one else. Tell them I sent you, and explain the symptoms, you know them as well as we do, and you know what was checked.”   [to be continued...]

Measuring voltage and how to use a digital multimeter (DMM) can be confusing to a beginner and potentially dangerous depending on what you happen to be measuring the voltage of. For example if you are measuring the voltage inside a television set or other device that has a Cathode Ray Tube (CRT) there will be voltages on the order of 10’s of thousands of volts. Anything that is plugged into a standard wall outlet (115V in US or 230V in UK for example) can kill you.

Click here for more information on the very informative book, Testing Electronic Components.

I don’t know about you, but I like small, medium and large as size names. Starbucks uses Tall, Grande and Venti as their size names. How to decipher that? Below is a table showing you the sizes of the drinks. All volumes are in ounces.

Here are a few things to notice:

1. The Cold drink Venti is larger than the Hot drink Venti. So if you’re buying for kids (as my wife often does) it is cheaper to order the Venti size and ask for another cup. The real trick is to get the kids to agree on a drink so that you can split it.
2. I’ve read in a couple of different locations that the name Venti® derives from the Italian word for twenty, spelled exactly the same (without the uppercase): venti. If anyone knows for sure, post a comment and tell us how you know. Let’s prove or disprove the urban legend.
3. You can only get the short (8 ounce) size drink by asking for it by name. If you request small, you’ll get a tall. You can only get the small for the hot drinks.

If you want to see the nutritional information for anything served at starbucks, goto: http://www.starbucks.com/retail/nutrition_info.asp there is a link for food and one for drinks.

If you want to understand all the lingo that starbucks uses with respect to their beverages, here is a great link: http://www.quicksilverweb.net/sbucks/sbcharts.htm

Silicon General Purpose NPN Transistor

This NPN bipolar junction transistor is designed as a general purpose amplifier and switch. The useful dynamic range extends to 100 mA as a switch and to 100 MHz as an amplifier.

Bipolar Junction Transistor -NPN

.Datasheet

General Purpose NPN Transistor

2N2219A, 2N2221 and 2N2222A are silicon planar epitaxial NPN transistors in JEDEC TO-39 (for 2N2219A) and in JEDEC TO-18 (for 2N2222A) metal case. They are designed for high speed switching and small signal applications at collector current up to 500mA, and feature useful current gain over a wide range of collector current, low leakage currents and low saturation voltage.

NPN

Datasheet